1. Dead zone analysis of ECAL barrel modules under static and dynamic loads Marc Anduze, Thomas Pierre Emile – LLR CALICE Collaboration September 25-27th 2017

2. Purpose
Optimize the hermiticity of the ECAL by reducing as much as possible dead zones of the detector, in particular gaps between each modules of the ECAL (barrel & Endcaps) under environmental loads.
Installing the ILC and the associated detector(s) in Japan requires to take into account seismic hazard when designing the instruments
So, all systems have to be designed to resist to vertically applied loads (gravity) but also horizontal seismic loading because seismic loads (dynamic) can induce forces with the same order of magnitude or higher than gravity.
We need to estimate the gap  and  which are required for ECAL assembly and to avoid mechanical contacts over the ECAL lifetime
ECAL Endcap2  
ECAL Endcap1
ECAL barrel
Sept 25-27th 2017
Marc Anduze

3.   Analysis Procedure  Z Gap  analysis in STATIC CASE
One static load is expected : Gravity
Impact the gaps in phi angle due to vertical loads (initial value : 2.5mm for BL)
Gap  analysis in DYNAMIC CASE
One dynamic load is expected : Acceleration spectrum from earthquake
Impact the gaps in Z direction due to horizontal ground motion (initial value : 1 mm for BL)
Initial gap between
2 ECAL modules in phi : 2,5 mm
Initial gap between
2 ECAL rings along Z : 1 mm  Z  
Sept 25-27th 2017
Marc Anduze

4. Static case model (Gap )
Model definition & simplifications:
Limited to HCAL+ECAL barrel (no impact of other elements)
ECAL model used is equivalent 3D solid model (simplified model)
Both SDHCAL and AHCAL are used (Two designs : VIDEAU and TESLA) to compare the impact of the geometry
Shell elements are essentially used
Every sub elements are supposed to be perfectly fixed together (no relative motion allowed between differents parts)
SDHCAL model :
VIDEAU geometry
Mass = 750 t
AHCAL model :
TESLA geometry
Mass = 705 t
Sept 25-27th 2017
Marc Anduze

5. Static case results (Gap )
Preliminary Analysis Results:
VIDEAU model :
Total displacement 0,9 mm Smallest gap between ECAL modules in phi : 2,31mm
TESLA model :
Total displacement 6 mm Smallest gap between ECAL modules in phi : 0,95 mm
SDHCAL design seems to be stiffer and reduces ECAL modules relative motion :
Best case to optimise the gap 
Sept 25-27th 2017
Marc Anduze

6. Dynamic case model (Gap )
Model definition & simplifications:
Model based on ILD baseline geometry ;
Limited to TESLA case for the barrel (more flexible model) and central part of the yoke ;
Shell elements are essentially used ;
Every sub elements are supposed to be perfectly fixed together (no relative motion allowed between differents parts) ;
Response Spectrum : Input taken from « Standard Reference Earthquake Parameters » Toshiaki TAUCHI, April Lyon
HCAL barrel
(TESLA Case)
Central ring of YOKE
Coil
Rails
ECAL
barrel
ILD model :
Mass = 3100 t
earthquake peak : 2-6 Hz
(maximum stresses)
Sept 25-27th 2017
Marc Anduze

7. Dynamic case Results (Gap )
Preliminary Analysis Results: Eigen Modes (states of excitation/vibration under specified fixed frequencies called resonant frequencies)
Mode 2,3Hz
Mode 3,05Hz
Mode 3,8Hz
Mode 7Hz
Due to the very heavy structure, 6 global modes are included into the range
of earthquake peak 2-6 Hz
Sept 25-27th 2017
Marc Anduze

8. Dynamic case Results (Gap )
Preliminary Analysis Results: Response spectrum - detector axis (Z) only
With the acceleration response spectrum applied along Z axis, the fundamental mode of the structure dominates: back and forth motion of the yoke ring
Maximum displacement: 24,9 mm
Smallest gap between ECAL rings along z: 0,98 mm
Smallest gap between ECAL module along phi: 2,29mm
No relative motion along Z between ECAL modules. The barrel follows the global motion of the YOKE+HCAL
Attaching the 3 rings together is probably the way to go to increase the overall stiffness and reduce the peak displacement
Sept 25-27th 2017
Marc Anduze

9. Dynamic case Results (Gap )
Preliminary Analysis Results: Response spectrum – Lateral only
With the acceleration response spectrum applied along lateral axis, the mode 2 of the structure dominates: left to right motion of the barrels
Maximum displacement: 17,3 mm
Smallest gap between ECAL rings along z: 0,98 mm
Smallest gap between ECAL module along phi: 1,89mm
No significant Z relative motion in traverse direction between ECAL modules
Sept 25-27th 2017
Marc Anduze

10. Dynamic case Results (Gap )
Preliminary Analysis Results: Response spectrum - Up and down only
With the acceleration response spectrum applied along third axis, the displacement is significantly lower (less than 3 mm).
Maximum displacement: 2,9 mm
Smallest gap between ECAL rings along z: 0,98 mm
Smallest gap between ECAL module along phi: 2,05 mm
The yoke ring offers a good resistance to side loading
No Z relative motion between ECAL modules too (same complete barrel behaviour)
Sept 25-27th 2017
Marc Anduze

11. Summary
Gravity and Earthquake are the major environmental loads that need to be taken into account when designing instruments (to be installed in Japan) for dimensions, stresses impact and deformations.
Static and dynamic analysis are used to study the relative motion between ECAL modules of the barrel (clearances definition):
For gap  : The behavior is dominated by static loads. Both geometries of HCAL are correct, if the initial gap is 2,5 mm, with a stiffer behavior for Videau case.
For gap  : The variation of gap is dominated by seismic loads but not significant relative motion has been detected in response spectrum along the 3 main axis
Next step:
We have also to combine static and dynamic analysis in order to have the behavior as close as possible to the reality.
Sept 25-27th 2017
Marc Anduze